In communications systems, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications system is deployed.
For example, for future generations of mobile communications systems frequency bands at many different carrier frequencies could be needed. For example, low such frequency bands could be needed to achieve sufficient network coverage for users (e.g. wireless devices) and higher frequency bands (e.g. at millimeter wavelengths (mmW), i.e. near and above 30 GHz) could be needed to reach required network capacity. In general terms, at high frequencies the propagation properties of the radio channel are more challenging and beamforming both at the network-side (e.g. at transmission points or access nodes) and at the user-side might be required to reach a sufficient link budget.
In mobile communications systems having a beam centric design, users may be operatively connected to the network by, and perform handover between, narrow beams instead of cells. At high frequencies, where high-gain beamforming will be needed due to more challenging radio channel propagation properties, each such narrow beam will only be optimal within a small area covered by the narrow area and the link budget for a user using the narrow beam but being located outside the small area will deteriorate quickly. Hence, a frequent and fast beam switching method is needed to maintain high performance, so called beam management.
The purpose of beam management is to keep track of users communicating with the network using narrow beams in order to increase the network coverage and throughput. Due to rotation, movement and blockage of the users, the beam (at the network-side and/or at the user-side) needs to be updated dynamically in order to maintain good channel quality between the network and the user. In case a user loses beam connection with the network, for example due to blockage, a beam recovery procedure can be initiated to re-establish the beam connection. Such beam recovery procedure can for example involve all beam combinations of the beams used at the user-side and the beams used at the network-side to be swept through in order for the best combination to be selected. When there are many candidate beams at both the network-side and the user-side, such a beam sweeping procedure (also referred to as beam training procedure) can be very costly in terms of time consumption and overhead signaling.
Hence, there is still a need for mechanisms enabling the beam sweeping procedure to be improved.